||Significant Revisions Made to Sheet and Strip Steel Standards
ASTM International Subcommittee A01.19 on Sheet and Strip Steel has made three significant changes to ASTM standards under its jurisdiction. The changes are:
• Reporting of boron levels made mandatory;
• Changes to size limitations of general requirements and product standards for hot rolled material; and,
• Addition of grades 90 and 100 for hot rolled sheet and strip products.
Subcommittee A01.19 is part of ASTM International Committee A01 on Steel, Stainless Steel and Related Alloys.
Boron is often added to low carbon steels to achieve lower hardness and increased formability; however, the mechanical properties of cold reduced and annealed material produced from hot rolled coils containing boron are affected by its presence. The differences may or may not be desired, but the effects are important and cold rolled steel manufacturers need to be informed of the presence of boron.
In recognition of the effects of boron on hot rolled and cold rolled mechanical properties, Subcommittee A01.19 modified three standards to require that boron analysis be conducted and the results reported. No limits were set for boron content. These standards are A 1008/A 1008M, Specification for Steel, Sheet, Cold-Rolled, Carbon, Structural, High-Strength Low-Alloy, High-Strength Low-Alloy with Improved Formability, Solution Hardened and Bake Hardenable; A 1011/A 1011M, Specification for Steel, Sheet and Strip, Hot-Rolled, Carbon, Structural, High-Strength Low-Alloy, High-Strength Low-Alloy with Improved Formability, and Ultra High Strength; and A 1018/A 1018M, Specification for Steel, Sheet and Strip, Heavy-Thickness Coils, Hot-Rolled, Carbon, Commercial, Drawing, Structural, High-Strength Low-Alloy, High Strength Low-Alloy with Improved Formability and Ultra High Strength.
Size Limitation Changes
The general requirements for hot rolled sheet and strip products are spelled out in Standards A 568/A 568M, Specification for Steel, Sheet, Carbon, Structural, and High-Strength, Low Alloy, Hot-Rolled and Cold-Rolled, General Requirements for, and A 635/A 635M, Steel, Sheet and Strip, Heavy-Thickness Coils, Hot-Rolled, Carbon, Structural, High-Strength Low-Alloy, and High-Strength Low-Alloy with Improved Formability, General Requirements for.
These standards were changed to make them clearer and easier to use. A 568/A 568M now covers all product with thickness less than 0.230 inches [6.0 mm] with no width limitation. A 635/A 635M applies to all product with thickness 0.230 inches [6.0 mm] and greater. The tolerances for product sizes that formerly were in A 635/A 635M were transferred to A 568/A 568M without change.
With this change, product standards A 1011/ A 1011M and A 1018/A 1018M are also affected. All hot rolled sheet ordered with thickness less than or equal to 0.230 inches [6.0 mm] is now governed by A 1011/A 1011M. It is recommended that users consult with the producer regarding these changes.
Ultra-High Strength Steel Grades
Standards A 1011/A 1011M and A 1018/A 1018M were changed to include grades with 90 and 100 ksi [620 and 690 MPa] minimum yield strength. These grades have the designation ultra-high strength (UHSS) as a way to differentiate them from the high strength low alloy with improved formability (HSLAS-F) designation. The UHSS grades may achieve their high strength by some measure of transformation strengthening and so do not strictly fit within the HSLAS-F group. The new UHSS grades are available in Types 1 and 2, each with particular limits on strengthening elements. Users should refer to the standards for details regarding composition limits and mechanical properties requirements.
Technical Information: David Overby, Lake Erie Steel, Nanticoke, Ontario, Canada
ASTM Staff: George Luciw
May 21-24, 2007
May Committee Week